There exist many gels which can be cooled to freezing and which absorb heat during warmup. These gels are placed in sealed envelopes or pockets and are employed as a reuseable coolant for portable iceboxes and the like. There are a number of different types of such gels. Some of them freeze solid, and some are flexible even at 0 degrees F. Such gels are usually packaged in a vinyl or other synthetic polymer composition flexible material so that the gel does not escape at any time. These freezing gel packages can be reused many times. They can only be employed as coolant in an icebox because of the size and shape of the envelope structures. The envelopes in which the gels are enclosed are of fairly large dimension so that they must be laid flat in the freezer or they will slump into a shape which is difficult to use in the icebox. There has been no constraint of the gel other than to prevent it from escaping the envelope.